Drafting instrument



Oct. 15, 1968 J. PFEFFER DRAFTING INSTRUMENT Filed May 19, 1966 INVENTOR JOHN PFEFFE/Z,

BY MYM M2 42,

ATTORN E YS United States Patent 3,405,447 DRAFTING INSTRUMENT John Pfefier, 659 Airport Road, Erlanger, Ky. 41018 Filed May 19, 1966, Ser. No. 551,258 3 Claims. (Cl. 3341) This invention relates to a drafting instrument which may be used to draw simultaneously a plurality of parallel lines with a predetermined spacing between each line which can be varied between relatively wide limits.

The drafting instrument of the present invention finds particular utility as a lettering guide, and in this embodiment three parallel guide lines are made simultaneously, and means are provided for varying the spacing between the lines in order to permit lettering of all sizes ordinarily encountered in engineering drawings and blueprints. However, it should be uderstood that the utility of this invention is not so limited, and other embodiments of the invention can be used for simultaneously drawing staff lines for music, guide lines for lettering in architectural drawings, and the like.

It is a principal object of the invention to provide a drafting instrument having a plurality of writing points for drawing simultaneously a plurality of parallel lines which are spaced apart from each other by distances which may be varied at -will.

It is a further object of the invention to provide a drafting instrument which can be used as a lettering guide, wherein the parallel lines may be drawn simultaneously with the required relative spacings between lines preserved regardless of the total spacing between the two outermost lines, and to provide simple means for varying the spacing between the outermost lines from any desired distance between about one-eighth inch and about one and one half inches.

It is another object of the invention to provide a drafting instrument having means for applying equal pressure or force upon each of the writing instrumentalities so as to ensure simultaneous scribing of a plurality of parallel lines of equal intensity.

With the above and other objects in view, as will become apparent to a person skilled in the art upon reading these specifications, the invention intended to be protected consists of the features of construction, the parts and combinations thereof, and the mode of operation as hereinafter described or illustrated in the accompanying drawings, or their equivalents.

Referring to the accompanying drawings, wherein are shown the preferred but obviously not necessarily the only embodiment of the invention:

FIG. 1 is a perspective view of a preferred embodiment of the drafting instrument of the present invention adapted for use as a lettering guide;

FIG. 2 is a fragmentary side elevation of a portion of the embodiment of FIG. 1 with certain parts shown in broken lines illustrating a line drawing means mounted in a movable arm of the drafting instrument;

FIG. 3 is a fragmentary side elevation similar to FIG. 2, showing a modification of a line drawing means;

FIGS. 4 through 7 are fragmentary side elevations similar to FIG. 3 showing other modifications of a line drawing means;

FIG. 8 is an exploded side elevational view of the line drawing means of FIG. 2 with certain parts shown in broken lines;

FIG. 9 is a fragmentary side elevation with certain parts shown in broken lines illustrating ink assemblies mounted in the movable arm for use in drawing staff lines for music; and

FIG. 10 is a cross-sectional view taken on the line 1010 of FIG. 1.

Referring to FIG. 1, a preferred embodiment of the drafting instrument comprises a base member 1 having a straight edge 10 which is moved along a conventional ruler or T-square 2 on a drawing surface such as a drafting table. Centrally mounted on the base member 1 is a cylindrical, rotatable pivot member 3. The pivot member 3 is provided with a vertical recess 4 dividing the pivot 3 into substantially equal segments from the top to a point substantially intermediate the topand bottom thereof. A horizontal bore 5 is provided perpendicular to the recess 4 passing through both segments of the pivot member 3. As best seen in FIG. 10, the base member 1 and the pivot member 3 are rotatably mounted with respect to each other by means of a threaded bore 6 in each member in which is engaged a screw 6a. The bore in the cylindrical member 3 is in the axis thereof.

A movable arm, generally designated as 10, comprises a straight first portion 7, which is provided with a horizontal bore 8 mating with the bore 5 in the cylindrical member 3. The arm 10 is pivotally mounted in the recess 4 of member 3 for vertically swingable movement by means of the pivot pin 5a, as shown in FIGS. 1 and 10.

A second or outer portion 9 of the movable arm 10 is preferably disposed at an angle which may vary between about 40 and 60 to the first portion 7 of the movable arm. The second portion 9 is adapted to receive a plurality of Writing assemblies, designated generally as 11. When using conventional stick lead, each writing assembly com- [prises a top knurled nut 12 having a threaded bore 13 therein through most of its length and a slightly reduced unthreaded bore 13a at the top thereof, as best illustrated in FIG. 8. A hollow cylindrical tube 14 is provided with threads 15 at its upper end for threaded engagement with the knurled nut 12. The tube 14 is further provided with threads 16 at its lower end for threaded engagement with a lower knurled nut 17 having a threaded bore 18 through most of its length and a slightly reduced unthreaded bore through the remainder of its length at the lower end thereof. A pair of slots 19 is formed in the upper end of the tube 14 so that the periphery of the tube 14 will be forced together slightly upon tightening the knurled nut 12 on the threads 15. A similar pair of slots 19 is provided at the lower end of tube 14, and a similar action occurs upon tightening knurled nut 17 on the threads 16.

As shown in FIGS. 2 through 7 the stick lead 20 is positioned inside the tube 14 and its free end may project upwardly through bore 13:: in the knurled nut 12 while the sharpened end will project through the bore 18a in the lower knurled nut 17. In the embodiment of FIGS. 1, 2 and 8, a compression spring 21 is positioned between the lower knurled nut 17 and the lower surface of the movable arm 10. The lead assembly is installed in vertically oriented bore 22 through the arm 10, and the spring 21 urges the point of the lead downwardly into cont-act with the drawing surface. The bore 22 is of uniform diameter throughout its length, and any desired number may be provided in the outer portion 9 of the arm 10. Bore 22 is of greater diameter than the tube 14, and hence the tube 14 is freely rotatable and axially movable within the bore. With the arrangement hereinabove described, it will be evident that the lead may be installed in the assembly 11 in such manner that the writing end of the lead 20 protrudes beyond the knurled nut 17 by a distance sufficient to contact the writing surface when the arm is in a horizontal position or depressed slightly below the horizontal position. Partial tightening of knurled nuts 12 and 17 cause the slotted ends of the tube 14 to grip the lead 20 in two positions holding it securely in its desired adjusted position. Further tightening of the knurled nut 12 then places the spring 21 under compression, thereby resiliently urging the point of the lead 20 against the writing surface. The force or pressure exerted by the spring 21 upon the writing point 20 of the lead can be varied at will by tightening or loosening the knurled nut 12.

FIGS. 3-7 illustrate alternative equivalents of the compression spring 21 disclosed in the embodiment of FIGS. 1, 2 and 8. In FIG. 3, a tensionspring 21a is provided which is positioned between the bottom of the upper knurled nut 12 and the upper surface of the movable arm 10. In FIG. 4, a resilient sleeve 21b of sponge rubber, foam rubber or foam synthetic material is substituted for the compression spring 21 and functions in the same manner. In FIG. 5, a leaf spring 210 having a bifurcated tip is afiixed to the lower surface of the movable arm 10, and the tip straddles the tube 14 so as to bear against the upper surface of the lower knurled nut 17, thereby urging it downwardly. In FIG. 6 a leaf spring 21dhavirig abifurcated tip is attached to the upper surface of the movable arm 10 with the bifurcated tip straddling the lead and bearing against the top of the upper knurled nut 12, thereby urging the lead assembly downwardly. In FIG. 7 an oversize nut 21e of lead or other heavy metal is substituted for the upper knurled nut 12, thereby urging the lead assembly downwardly by force of gravity. Although not illusstrated in the drawings, a further equivalent is the provision of a magnetic tape material on the upper surface of the movable arm 10 which would attract the upper knurled nut 12 when made of magnetic material.

In the preferred embodiment of the invention, as shown in FIG. 10, a compression spring 23 is positioned in a cylindrical bore 24 formed at the base of the recess 4 in the cylindrical pivot member 3. The spring 23 urges the arm 10 upwardly to a position slightly above the horizontal, so that the lead points do not bear against the writing surface when the instrument is not in use.

In the embodiment of FIG. 9, which is adapted for use in drawing stafl lines for music, five vertically oriented bores 22 are provided in the movable arm 10, and the spacing between each bore is uniform. Pen points 20a, each having a small reservoir of ink, similar to pen points provided in the Leroy lettering systems, may be substituted for the stick leads 20 of the embodimentof FIGS. 1 and 2. so that permanent staff lines may be drawn. In all other respects, the embodiment of FIG. 9 functions in the same manner as that of FIGS.'1 and 2.

The instrument is preferably also provided with means for predetermining the spacing between the outermost pair of lines, or the spacing'between adjacent lines. As shown in FIG. 1, indicia 25 are provided for this purpose on the base member 1 surrounding thecylindrical pivot member 3. The pivot member 3 is provided with'a pointer 26 which indicates the proper position to which the pivot member 3 and the attached arm 10 should be turned. The indica may indicate, for example, the distance between the top and bottom lines in fractions of an inch when the instrument is being used as a lettering guide. Any other convenient units of measurement could be provided in connection with the indicia.

In order to use the drafting instrument, the draftsman will first align the ruler or T-square 2 in the proper position on the drawing surface, and the drafting instrument 4 will be placed with its edge 10! against the upper surface of the ruler. The draftsman selects the proper spacing by rotating the member 3 relative to the base 1 to a setting shown by indica 25 and pointer 26. He then draws the parallel sets of lines by applying light downward pressure to the movable arm 10 and sliding the base member 1 along the straight edge 2 with the edge 1a in contact with the straight edge at all times. Upon release of the light pressure, the spring 23 will move the arm 10 upwardly a distance sufficient to raise the points of the leads or pens from the drawing surface.

As indicated above, the distance which each lead 20 or pen 20a protrudes beyond the knurled nut 17, and the resilient biasing force or pressure exerted by each spring 21, 2111-2111, are adjustable individually and separately for each assembly 11. This makes it easily possible to provide uniform intensity of all the parallel lines.

It will be understood that the movable arm 10 need not be formed with the outer portion 9 at an angle with respect to the first portion 7. The arm '10'could be a straight'member throughout its length, but in this event it is necessary to swing the movable arm to a position'where it forms a very small acute angle with respect to the longitudinal axis of the base' 1 in order to produce lines having minimal spacing therebetween. The angular arrangement between portions 7 and 9 illustrated in FIG. 1 is thus the preferred arrangement, and it will be evident that the maximum spacing between parallel lines is obtained in this embodiment when the arm 10 is swung to a position in which the outer portion 9 is perpendicular to the ruler 2.

distance between the middle and lowermost bore. If a plurality of five uniformly spaced bores is provided, it is evident that three stick lead assemblies may be positioned in three of the bores with the desired relative spacing therebetween. In order to provide sufiicient spacing between guide lines for all lettering sizes normally encountered, the outermost pair of bores preferably is positioned about one and one-half inches apart. This would constitute the maxmum spacing between lines, and it will be evident that there is no limitation on the minimum spacing between lines. Indeed, the member 3 and attached arm 10 can be rotated far enough to the left in FIG. 1 to align all three line drawing means and thereby draw only one line.

Modifications may be made in this invention without departing from its scope and spirit. For example, while the embodiments illustrated in the drawings provide an individual resilient element 21, 21a 21d for each line drawing assembly, it is within the scope of the invention to provide a single resilient means such as a leaf spring contacting all the assemblies and biasingthem toward the drawing paper. Instead of providing the compression spring 23 in the bore 24 at the base of recess 4 in the pivot member 3, the portion 7 of the arm 10 could be extended and provided with a weight counterbalancing the portion 9 of the arm and the drawing assemblies 11.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A drafting instrument comprising a base member having an edge adapted to slide along a stationary straight edge, a pivot member mounted for rotation on said base member, a movable arm pivotally attached adjacent one end thereof to said pivot member for swingable movement in a vertical plane, a plurality of line drawing means at tached along said movable arm adjacent the other end thereof in spaced apart relation to each other, each said line drawing means comprising a stick lead, a tube surrounding said stick lead, first clamping means threadably engaging the top of said tube and clamping the periphery thereof around said lead, second clamping means threadably engaging the bottom of said tube and clamping the periphery thereof around said lead, whereby to hold said lead in a selected position of adjustment, and biasing means comprising a resilient element urging one of said clamping means toward a drawing surface.

2. The drafting instrument claimed in claim 1, wherein said first clamping means threadably engaging the top of said tube is a threaded nut, rotation of which acts to vary the biasing pressure exerted by said resilient element.

3. The drafting instrument claimed in claim 1 including a plurality of vertical bores through said other end of said movable arm of greater diameter than said tubes, each said tube being disposed within a bore, said first and second clamping means being disposed above and below said bore respectively, and wherein said resilient element is disposed between one of said engaging means and said arm.

References Cited UNITED STATES PATENTS 1,619,750 3/1927 Nelson 33158 2,407,594 9/1946 Whiteley 3341 2,551,747 5/1951 Ille 33-41 2,869,237 1/1959 Berge.

3,164,906 1/ 1965 Andaloro.

FOREIGN PATENTS 120,791 2/ 1948 Sweden.

WILLIAM D. MARTIN, JR., Primary Examiner. 

1. A DRAFTING INSTRUMENT COMPRISING A BASE MEMBER HAVING A EDGE ADAPTED TO SLIDE ALONG A STATIONARY STRAIGHT EDGE, A PIVOT MEMBER MOUNTED FOR ROTATION ON SAID BASE MEMBER, A MOVABLE ARE PIVOTALLY ATTACHED ADJACENT ONE END THEREOF TO SAID PIVOT MEMBER FOR SWINGABLE MOVEMENT IN A VERTICAL PLANE, A PLURALITY OF LINE DRAWING MEANS ATTACHED ALONG SAID MOVABLE ARM ADJACENT THE OTHER END THEREOF IN SPACED APART RELATION TO EACH OTHER, EACH SAID LINE DRAWING MEANS COMPRISING A STICK LEAD, A TUBE SURROUNDING SAID STICK LEAD, FIRST CLAMPING MEANS THREADABLY ENGAGING THE TOP OF SAID TUBE AND CLAMPING THE PERIPHERY THEREOF AROUND SAID LEAD, SECOND CLAMPING MEANS THREADABLY ENGAGING THE BOTTOM OF SAID TUBE AND CLAMPING THE PERIPHERY THEREOF AROUND SAID LEAD, WHEREBY TO HOLD SAID LEAD IN A SELECTED POSITION OF ADJUSTMENT, AND BIASING MEANS COMPRISING A RESILIENT ELEMENT URGINH ONE OF SAID CLAMPING MEANS TOWARD A DRAWING SURFACE. 